Calutron



Aug. 25, 1959 Filed June 28, 1946 L. R. LUDWIG ET AL 2,901,618

CALUTRON 2 Sheet-Sheet l INVENTORS Leon R.Lzldwz '9' 4 Royal GffieryvqllCALUTRON Filed June 28, 1946 2 Sheets-Sheet 2 'INVENTORS Lean 1Q. Ludwig&

BY Royal ffiergv' ll United States Patent CALUTRON Leon R. Ludwig,Buffalo, N.Y., and Royal C. Bergvall, Pittsburgh, Pa., assignors, bymesne assignments, to the United States of America as represented by theUnited States Atomic Energy Commission Application June 28, 1946, SerialNo. 679,974

4 Claims. (Cl. 250- 113) This invention relates to calutrons andparticularly to a tank and liner assembly that encloses the operatingelements of apparatus of this kind.

By the term calutron is meant apparatus for separation on a practicalscale of different isotopes of a material, or separation of suchmaterial into components that are respectively enriched and impoverishedin their con.- tents of a given isotope, such separation orconcentration being accomplished by means of a beam of acceleratedgaseous ions projected through a magnetic and/or an electric field,whereby ions of different masses are caused to follow curved paths ofdifferent radii and respectively come to a focus at predetermined spacedpositions so as to permit collection of the respective components atthese positions and thereby effect separation.

Such apparatus includes a tank that encloses a highly evacuatedoperating chamber, means for projecting one or more beams through thechamber, magnet for setting up a field that extends through the chamberin a direction normal to that in which the ions are projected, and acollector for separating and retaining the portion of each beam thatcontains the greatest concentration of the desired isotopic component,and de-ionizing the charged particles that make up the collected portionof the beam.

Due to the tendency of the ions forming the beam to scatter, and alsodue to sputtering of de-ionized material from the collecting apparatus,and also due to condensation of unionized gas, material is deposited onthe surfaces enclosing the apparatus, making it necessary to clean thesurfaces of the structure enclosing the operating systenr. The materialobtained by such cleaning is reprocessed in the apparatus. sorbed by thetank walls to be released during operation, by reason of the relativelyhigh operatingternperature, the high vacuum maintained in the tank.during operation, and bombardment by scattered ions, which gas tends tointerfere with the orderly travel of the ions and may contaminate theproduct. Such considerations render it desirable to provide a liner,arranged inside the tank, enclosing. a processing space that isseparated from the inner surfaces of the tank and wherein the operatingelements of the system are arranged, and that is readily removable toprovide easy access to its interior for cleaning of its interiorsurfaces.

One object of the invention is the provision of a novel arrangement ofan assembly of a tank and liner, which separates a processing spaceenclosed by the liner from exposure to the inner surfaces of the tankwalls, and which provides for removal of gas molecules released from theinner surfaces of the tank walls by direct paths that communicate with avacuum system arranged outside the tank, thereby substantiallyeliminating the possibility of such molecules entering the processingspace and preventing their interference with the ion beam.

Another object is the provision of an assembly of this kind arranged topermit removal of the liner by a simple Withdrawing movement.

There is a tendency for gas ad- 1 2,901,618 Patented Aug. 25, 1959 ICCStill another object is the provision in a calutron of an arrangement oftank and liner which provides both for ready removal of the liner, andfor establishment of separate paths of communication between a singlepump-out connection to a vacuum system and spaces that are respectivelyinside the liner and between the outer surfaces of the liner and theinner surfaces of the tank.

In the accompanying drawings:

Fig. 1 is a sectional elevation of a calutron tank sembly arranged inaccordance with the present invention. Fig. 2 is a sectional view online 2-2 of Fig. 1. i I Describing the drawings in detail, a calutrontank is illustrated diagrammatically as comprising side walls 5 that areparallel and spaced apart by an intermediate structure including spacingstruts 6, opposed Walls 7 defining edges of the chamber, and an end wall8. These walls cooperate to enclose an operating chamber having an openend 9. The open end 9 is closed by a face plate structure 10 that issealed to the tank and on which the operating elements of the system aremounted, so that they may be removed from the tank as a unit with theface plate. The end wall 8 is provided with a pump-out connection 11,which is a tubular structure opening into the operating chamber at 12and the walls 13 of which join the end wall 8.

The operating system of the calutron is diagrammatically illustrated ascomprising a casing 14 that encloses sources for projecting beams ofaccelerated ions, and a second casing 15 that encloses receivers 16 forseparately collecting and de-ionizing the desired components of therespective ion beams, such beams being curved through in their passagethrough the operating chamber by a powerful magnetic field that extendsbetween the side walls 5 and is therefore normal to the direction inwhich the beams are projected. A baffle structure 17 is arranged acrossthe opening 25 to shield it from the beam.

The operating system is enclosed within a processing space set off fromthe tank walls by a liner 18, which is slidably mounted in the tank forremoval through the open end 9, and comprising walls that respectivelycorrespond to each of the walls of the tank. These walls include twoside walls 19, two side walls 21 and end wall 20; The side Walls 19, 21are jacketed by walls 22 intermediate the sides 19, 21 and tank walls 5and 7. The end of the liner adjacent the open side of the tank is closedby the face plate 10. The internal surfaces of the walls 19,

20 and 21 are smooth planes, permitting ready cleaning to reclaim thematerial that collects on such surfaces during operation. Heat transferjackets 22 are applied to the external surfaces of the walls, andconnected to a temperature-regulating fluid system by headers 23' respectively connected to supply and exhaust pipes 24' that extend throughthe" face plate 10.

The end wall 20 of the liner is interrupted to provide an aperture 25that registers with the opening 12 of the pump-out connection. Thisaperture 25 is surrounded by a tubular extension 26 of the liner thatprojects into the pump-out connection 11 to a point beyond the end wall8 of the tank.

Each of the walls of the liner 18 is spaced inward from thecorresponding wall of the surrounding tank, so that spaces 27 liebetween the outer surfaces of the liner walls and the inner surfaces ofthe adjacent tank walls. Similarly, the outer surfaces of the tubularextension 26 are spaced inward, transversely of the extension, from theinner surfaces of the pump-out connection 11, providing passages 28 thatopen at one end into the pump-out connection and at the other into thespaces 27. By this arrangement, separate paths of communication areprovided, one of which connects directly between the pump-out connectionand the processing space enclosed by the liner,

the other connecting directly between the pump-out connection and thespaces 27. This provides a 10w impedance path to the pump-out connectionfor gas mole cules released from theinner surfaces of the tank walls,while high impedance is presented by the liner walls to the passage ofsuch molecules to the processing space. The arrangement also provides anentirely separate low impedance path from the processing space to thepumpout connection. a

Preferably the liner Walls are made of a metal that is non-magnetic andthat presents smooth, nonporous surfaces having low gas adsorbingproperties, and permitting ready cleaning of material deposited eitherby deionization or condensation. Stainless steel is a suitable material,since it may be easily cleaned, may be given a smooth surface andreadily releases gas molecules during evacuation of the tank. Release ofgas from the liner Walls may be accelerated by passing a current of hotfluid through the jackets 22 during evacuation, instead of the coolingliuid that is normally used during operation.

The described arrangement of a liner is peculiarly advantageous becauseit solves the problem presented by interference with the ion beam bymolecules released from the tank walls during operation of the calutron.Removal of gas from the thin stainless steel walls, which can readily beheated, is quite easily accomplished. The tank walls, however, are notas readily cleaned of adsorbed gases, particularly the side walls 5.These walls are ordinarily made of magnetic material to enable them toact as pole pieces between which the magnetic field is established. Theyare also of thick cross section, so that it is impractical to heat themduring evacuation of the tank to drive off gas molecules. Since tanks ofthis kind are usually very narrow in the direction extending between theside walls, they are inaccessible and it is also difficult to clean theinner wall surfaces. The arrangement described above provides forremoval of gas molecules released from all of the tank walls, andadditionally of gas that may leak into the tank, in such a way as topractically eliminate the possibility of interference with the ions orcontamination of the product.

It is to be noted that the extension 26 of the liner projects in thedirection in which the liner is moved during its insertion into thetank, so that the assembly of the liner and its extension with the tankand tubular pumpout connection is made telescopically by a straight linea liner arranged within the tank to surround a processing space, saidliner having its outer surfaces spaced inward from the inner surfaces ofthe tank, and the space between the said surfaces of the liner and tankopening directly into the pump-out connection to provide a low impedancepath for gas molecules released from said surfaces during evacuation ofthe tank.

2. In a calutron assembly comprising a tank enclosing an operatingchamber and provided with a tubular pumpout connection opening into saidchamber for evacuating it; a liner arranged within the tank to surrounda processing space, said liner comprising walls that are spaced inwardfrom the tank walls and having a tubular extension projecting into thepump-out connection of the tank, said extension opening into theprocessing space surrounded by the liner and its outer surfaces beingspaced inward from the Walls of the pump-out connection to establishseparate communication paths that respectively'connect the interior ofthe pump-out. connection with the processing space and with the spacebetween the tank walls.

3. In a calutron assembly comprising a tank formed of walls that enclosean operating chamber, and a tubular pump-out connection opening throughone of the walls; a liner arranged in the operating chamber andcomprising walls that respectively correspond to each of the tank walls,said walls enclosing a processing space and each being spaced inwardfrom the corresponding tank wall, said liner having a tubular extensionprojection into the pump-out connection and beyond the wall throughwhich movement of the liner into the tank. This arrangement permits theaccomplishment of the desired results, namely the provision of a directlow impedance path between spaces outside the liner and the pump-outconnection, which paths are separated by the extension 26 from theprocessing space to a point well beyond the limits of said connectionopens, said extension providing internal direct communication betweenthe pump-out connection and the processing space, and its outer surfacesbeing spaced inward from the inner surfaces of said connection toprovide direct external communication between the connection and thespace between the Walls of the liner and tank.

4. A calutron assembly comprising a tank structure that encloses anoperating chamber, said tank structure having an open end adapted to beclosed by a face plate and an end Wall opposite said open end, a tubularpumpout connection opening through said end wall and projectingoutwardly from it, a liner slidably mounted in the operating chamber forremoval through the open side, said liner comprising walls enclosing aprocessing space and that are spaced inward from the inner surfaces ofthe tank structure, said liner having a tubular extension opening intothe processing space and projecting into the pump-out connection, saidextension having its outer surfaces spaced inward from the innersurfaces of said connection, providing passages within the connectionthat are separated from the processing space and that communicate withthe spaces between the liner and tank structure.

References Cited in the file of this patent UNITED STATES PATENTS1,369,984 Schafer Mar. 1, 1921

